1. Field of the Invention
Embodiments of the present invention generally relate to supporting a gas distribution showerhead within a plasma chamber. More specifically, the invention relates to supplying a gas to the chamber through the gas distribution showerhead.
2. Description of the Related Art
Plasma enhanced chemical vapor deposition (PECVD) is a deposition method whereby processing gas is introduced into a processing chamber through a gas distribution showerhead. The showerhead is electrically biased to ignite the processing gas into a plasma. The susceptor, sitting opposite to the showerhead, is electrically grounded and functions as an anode. The showerhead spreads out the processing gas as it flows into the processing space between the showerhead and the susceptor.
PECVD has recently become popular for depositing material onto large area substrates. Large area substrates may have a surface area of greater than about one square meter. Large area substrates may be used for flat panel displays (FPDs), solar panels, organic light emitting displays (OLEDs), and other applications. These processes require the large area substrate be subjected to temperatures on the order of 300° C. to 400° C. or higher, and maintained in a fixed position relative to the showerhead during deposition to ensure uniformity in the deposited layers.
The showerhead is generally a perforated plate supported in a spaced-apart relation above the large area substrate adapted to disperse a process gas and typically has substantially the same area as the to-be-processed substrate. Showerheads are commonly made of aluminum and are subject to expansion and contraction while enduring the temperatures during the PECVD processes. Showerheads are commonly supported around the edges and a center to maintain the processing space between the substrate and the showerhead. However, the typical center support schemes affect gas flow through the showerhead. When gas flow is not distributed sufficiently through the showerhead during deposition, the process may not produce uniform deposition on the substrate, which may result in an unusable large area substrate.
Therefore, what is needed is an apparatus and method for supporting a gas distribution showerhead that maintains the processing space between the substrate and the gas distribution showerhead and does not interfere with gas flow through the gas distribution showerhead.